Lattice beam



July 7, 1931. c. L. WOOLDRIDGE LATTICE BEAM F iled Jan. 22, 1929 INVENTOR M I W wrrysssss Patented July 7, 1931 UNITED STATES PATENT OFFICE CHARLES L. WOOLDRIDGE, F PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 CHARLES I1. WOOLDRIDGE, INQ, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA Application filed January 22, 1929. Serial No. 334,248.

My invention relates to metal lattice beams such as are used in floor constructions and the like; and it isone of my objects to produce a metal lattice beam which will be an 6 improvement over those heretofore proposed in simplicity and ease of construction, as well as in the cheapness of the materials employed therein. It is another object of my invention to produce a metal lattice beam which,

'1 while having the required strength, will be of exceptionally small weight.

By way of example, I have shown a form of lattice beam embodying my invention, together with several modifications thereof, in

in the accompanying drawings, in which:

Fig. 1 is a side elevation of a lattice beam constructed in accordance with my invention;

Fig. 2 is a section taken on the line 22 of Fig. 1, showing the manner of abutting the compression and tension chords of the beam at the ends, and securing them together;

Fig. 3 is a section on the line 33 of Fig. 1, showing a manner of securing the tubular struts to the webs of the chords;

Fig. 4 is a detail side elevation showing a modified construction of the ends of the chords;

Fig. 5 and 6 are an elevation and an end view respectively, showing a modified means of connecting the tubular struts with the webs of the chords;

Fig. 7 is a view similar to Fig. 6, but showing another means of connecting the tubular struts to the chords;

Fig. 8 is a cross section illustrating a modi-' fied form of the beam in which the chords are of a composite, instead of an integral, T-shape construction, and showing a means of securing the tubular struts to the webs of such composite chords; and

Fig. 9 is a view similar to Fig. 8 showing another modified means of securing the tubular struts to the chords.

Referring now to the drawings, and particularly t0 the form of my invention shown in Figs. 1 to 3 thereof, the lattice beam comprises a compression chord of T-shape in cross section and including a horizontal web 10 and a vertical web 11. Associated with the compression chord is a tension chord likewise of T-shape and including a horizontal web 12 and vertical web 13. The chords are preferably formed of rolled T-bar, and the tension chord is bent down as illustrated and connected, at that part, to the compression chord by struts in the well known manner. The ends of the web portion 11 of the compression member rest upon and abut edgewise against, the ends of the web portion 13 of the tension member, and are secured in such relation by means of fish plates 14 which are riveted to both web portions as indicated at 15. In this way an exceptionally simple and easy means of connecting the chords is provided, in which the compression chord rests solidly upon the tension chord and the longitudinal shear is taken by the rivets 15. It will be seen, moreover, that the horizontal web 12 of the tension chord forms a natural base upon which the beam may stand, without the necessity of special end bearing members.

The struts 16 consist of tubes, the ends of which are split, separated and flattened so as to form forks 17 which embrace the webs 11 and 13 respectively, and are secured thereto :by means of rivets 18 passing through the webs and the forked ends of the tubular struts. In the construction now being described, the ends of each adjacent pair of struts are placed close to each other, but do not overlap. By constructing the struts of tubes, flattened at their ends for connection with the ends of the chords in the manner above described, I am enabled to obtain, without sacrifice of strength, a construction of exceptionally small weight. The short lengths of tube are available on the market at low prices; and their use, taken in connection with the use of T or angle bars for the chords, provides a specially economical construction while still retaining all the desirable char-' acteristics of a beam of this kind.

In the modified construction shown in Fig. 1, the web sections 11a and 13a of the chords are formed with one or more serrations, indicated at 20, of complementary shape, so that the web sections interlock at the points of abutment. The longitudinal strain is thus taken, in this construction, by the webs themfall) selves.

construction.

In the construction shown in Figs. 1 to 3, and heretofore described, the ends of adjacent struts 16 are secured to the chords by separate rivets. It is advantageous under some conditions to employ the same rivets for securing the ends of adjacent struts to the chords. Constructions by means ofwhich this may be effected are shown in Figs. 5 to 7. In the form shown in Figs. 5 and 6 the struts are forked at the ends, as before, but

.the forked ends are enclosed one, in the other and made to embrace the web of the chords, a single rivet being passed through the whole. In the form shown in Fig. 7, the ends 19 of the struts 16 are flattened instead of being forked. In that event the ends of adjacent struts are placed upon opposite sides of the chord web, and may be secured by means of rivets 18?) passing through the chord and both strut ends.

In the modifications heretofore referred to, the chords are shown as being of integral T-shape construction. They may, however, be of a composite T-shane construction as illustrated in Figs. '8 and 9. These figures show the compression chord as consisting of a pair of angle bars. placed back to back so as to form a composite T-section having horizontal web portions 10?) and vertical web portions 116. If the ends of adjacent struts are to be secured to the chord webs by separate rivets as in Figure 1, the ends 19a of the struts may be flattened and insertedbetween the web portions 116, the whole being secured together by means of rivets 18a, as shown in Fig. 8. If the ends of adjacent struts are to be secured to the chord Webs by the same rivets, each adjacent pair of struts 16 may have their ends flattened and-offset in opposite directions as indicated at 19?) in Fig. 9. these ends being overlapped and in serted between the webs 11b of the chord, and a rivet being passed through the whole.

I claim as my invention:

A lattice beam comprising a tension chord of T-shape in cross section and having a single central vertical web portion formed with serrations at the ends, a compression chord having a single central vertical web portion formed at the ends with serrations complementary to those of said tension chord. said chords being associated with their said web portions abutting edgewise at the ends, each set of serrations engaging in the other set, a pair of plates at each end of the beam, said plates enclosing the web portions of said tension and compression chords bet-ween them, thereby to maintain said chords in vertical alignment, means for drawing said plates to gether to clamp said web portions, and struts connected between said ChQrds, said struts The serrated webs are secured toconsisting of tubes having the ends thereof gether by fish plates 14a, as in the preceding formed with flat portions for attachment to the vertical webs of said chords.

In testimony whereof, I sign my name.

CHARLES L. WOO-LDRIDGE. 

